Have you located one ? I assume you're clamping an additional one to the existing bar. I've added one to my 124E. It does make a difference.
Anyway, i have an extra if still looking. Can send to the border to help on shipping cost. Pete

Easy to make. (4) Aluminum blocks ( metal supply store will cut to size ). Drill two holes for s/bars. Two holes for bolt & nut clamping. Cut in half. Copy the one from Milton or i can give you basic dimensions off mine. Pete

If you can get the right sized aluminum block material you won't have to cut it in half. I did these ones up (can't remember the exact size of the aluminum) buy cutting the aluminum block/bar into 8 parts and bolting them together face to face to make four thick blocks, I mounted them firmly in a vice then drilled the ARB holes through them (between the two block parts).
I have not driven the car yet so I can't comment on how well it works?

I was a bit worried about the clearance when I installed the additional bar, I may need to make another set of blocks but tighter together. I will find out when I get her on the road??_________________Anglia 100e modified
Prefect 100e stock